svn commit: r300442 - head/bin/sh
Don Lewis
truckman at FreeBSD.org
Mon May 23 01:01:25 UTC 2016
Author: truckman
Date: Mon May 23 01:01:23 2016
New Revision: 300442
URL: https://svnweb.freebsd.org/changeset/base/300442
Log:
Hopefully fix Coverity CID 1008328 (Out-of-bounds write) in /bin/sh.
Replace the magic constant 127 in the loop interation count with
"PROMPTLEN - 1".
gethostname() is not guaranteed to NUL terminate the destination
string if it is too short. Decrease the length passed to gethostname()
by one, and add a NUL at the end of the buffer to make sure the
following loop to find the end of the name properly terminates.
The default: case is the likely cause of Coverity CID 1008328. If
i is 126 at the top of the loop interation where the default case
is triggered, i will be incremented to 127 by the default case,
then incremented to 128 at the top of the loop before being compared
to 127 (PROMPTLENT - 1) and terminating the loop. Then the NUL
termination code after the loop will write to ps[128]. Fix by
checking for overflow before incrementing the index and storing the
second character in the buffer.
These fixes are not guaranteed to satisfy Coverity. The code that
increments i in the 'h'/'H' and 'w'/'W' cases may be beyond its
capability to analyze, but the code appears to be safe.
Reported by: Coverity
CID: 1008328
Reviewed by: jilles, cem
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D6482
Modified:
head/bin/sh/parser.c
Modified: head/bin/sh/parser.c
==============================================================================
--- head/bin/sh/parser.c Mon May 23 00:58:52 2016 (r300441)
+++ head/bin/sh/parser.c Mon May 23 01:01:23 2016 (r300442)
@@ -1998,7 +1998,7 @@ getprompt(void *unused __unused)
/*
* Format prompt string.
*/
- for (i = 0; (i < 127) && (*fmt != '\0'); i++, fmt++)
+ for (i = 0; (i < PROMPTLEN - 1) && (*fmt != '\0'); i++, fmt++)
if (*fmt == '\\')
switch (*++fmt) {
@@ -2011,7 +2011,8 @@ getprompt(void *unused __unused)
case 'h':
case 'H':
ps[i] = '\0';
- gethostname(&ps[i], PROMPTLEN - i);
+ gethostname(&ps[i], PROMPTLEN - i - 1);
+ ps[PROMPTLEN - 1] = '\0';
/* Skip to end of hostname. */
trim = (*fmt == 'h') ? '.' : '\0';
while ((ps[i] != '\0') && (ps[i] != trim))
@@ -2061,8 +2062,9 @@ getprompt(void *unused __unused)
* Emit unrecognized formats verbatim.
*/
default:
- ps[i++] = '\\';
- ps[i] = *fmt;
+ ps[i] = '\\';
+ if (i < PROMPTLEN - 1)
+ ps[++i] = *fmt;
break;
}
else
More information about the svn-src-all
mailing list